(1) Field of the Invention
The present invention relates to a colorant used for the coloration of materials in the fields of paints, inks, plastics or coating materials used for the parts of IT equipment which utilizes light. More particularly, it relates to a method for producing a colorant excellent in color development by making the most of the inherent absorption spectrum of a coloring matter substance constituting the colorant.
(2) Description of the Related Art
The colored materials used in the above technical fields are generally produced either by a method of directly dispersing a coloring matter substance, such as a pigment or a dye, in a material mainly consisting of a resin, i.e. a binder, suitable for the purpose of use or by a method of previously preparing as above a colorant containing the coloring matter substance at high concentration and incorporating this colorant into a material mainly consisting of a resin, i.e. a binder suitable for the purpose of use.
Therefore, with a rapid advance of the purpose of use in the above fields, needs for the improvement in the quality of colored materials naturally lead to the requirement to develop a technically more advanced method for producing colorant than the above two methods.
It is widely acknowledged that for meeting the above requirement, there have been made efforts to develop a starting material for the coloring matter substance that can provide materials satisfying required delicate color tone and color intensity, and to develop a process for surface treatment of a coloring matter substance, a process for preparing a composite of coloring matter substances, a process for pulverization of a coloring matter substance, etc.
Furthermore, regarding a resin for binder which is another material controling the performance of the materials colored with a coloring matter substance, efforts have been made to develop a resin with less impurities which does not inhibit the performance of the coloring matter substance, i.e. a filler to be introduced (JP-A-2000-086706), and there has been proposed an ampholite resin to be used as a dispersing resin suitable for the dispersion of a coloring matter substance (JP-A-2000-026560).
Further, as to the above two methods for obtaining materials colored with these coloring matter substances, the following methods have been developed and put to practical use: a method which comprises removing impurities in a coloring matter substance by an ion exchange, followed by dispersing the coloring matter substance (JP-A-11-071468), a method which comprises enclosing a coloring matter substance with a resin to form micro-capsules (JP-A-10-298294, JP-A-2000-119141 and JP-A-7-316242), and a method of dispersing fine particles utilizing a dispersing machine (JP-A-2000-119571).